/Engine/Source/Developer/ShaderFormatOpenGL/Public/ShaderFormatOpenGL.h
Based on ShaderVersion decides what platform specific compiler to use
void PlatformCompileOffline ( const [FShaderCompilerInput](API\Runtime\RenderCore\FShaderCompilerInput) & Input, [FShaderCompilerOutput](API\Runtime\RenderCore\FShaderCompilerOutput) & ShaderOutput, const ANSICHAR * ShaderSource, const [GLSLVersion](API\Developer\ShaderFormatOpenGL\GLSLVersion) ShaderVersion )